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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script type="text/javascript" src="../js/vue.js"></script>
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    <script type="text/javascript">
        let data = {
            name:'尚硅谷',
            address:'北京',
        }

        //创建一个监视的实例对象，用于监视data中属性的变化
        const obs = new Observer(data)		
        console.log(obs)	

        //准备一个vm实例对象
        let vm = {}
        vm._data = data = obs

        function Observer(obj){
            //汇总对象中所有的属性形成一个数组
            const keys = Object.keys(obj)
            //遍历
            keys.forEach((k)=>{
                Object.defineProperty(this,k,{
                    get(){
                        return obj[k]
                    },
                    set(val){
                        console.log(`${k}被改了，我要去解析模板，生成虚拟DOM.....我要开始忙了`)
                        obj[k] = val
                    }
                })
            })
        }

    </script>
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